1. Field of the Invention
The present invention relates to an endoscopic imaging apparatus and a capsule endoscope which obtain an image inside a subject when the capsule endoscope is putted in the subject.
2. Description of the Related Art
Recently, instead of the conventional endoscope, a swallowing type endoscope, i.e., a so-called capsule endoscope receives attention because pain of a subject can be reduced and so on. For example, as shown in FIG. 21, in the capsule endoscope, a wiring board 2 and a power source 3 are accommodated in a sealed container 1 formed in a capsule shape. A functional circuit is formed on the wiring board. The capsule endoscope is configured to obtain the image inside the subject as being the test body while the capsule endoscope is putted in a body cavity of the subject. The sealed container 1 includes a cylindrical container main body 1a having a bottom and a front cover 1b molded by an optical material. The sealed container 1 is configured to attach the front cover 1b to a front portion of the container main body 1a while watertightness is secured between the container main body 1a and the front cover 1b, after the wiring board 2 and the power source 3 are accommodated in the container main body 1a. The sealed container 1 is formed in a size to an extent in which a human can swallow the sealed container 1, and both end portions of the sealed container 1 are formed in a hemispherical shape. In order to form a circuit of the above-described functions circuit, various functional components and electronic components such as an illumination unit 4, a lens unit 5, an imaging device 6, and a wireless transmission unit 7 are mounted on the wiring board 2.
In the case of use of the capsule endoscope, the subject can swallow the capsule endoscope while a power source 3 is turned on. When the capsule endoscope is putted inside the body cavity of the subject, while an observation range of the subject such as the stomach, the small intestine, and the large intestine is illuminated with illumination light emitted from illumination unit 4 through the front cover 1b until the capsule endoscope is discharged to the outside of the body, reflected light incident through the front cover 1b is focused to an imaging device 6 through a lens unit 5, and the reflected light focused to the imaging device 6 is output as an image signal. Then, the image signal output from the imaging device 6 is wirelessly transmitted to the outside by a wireless transmission unit 7, and image information on the subject can be received and observed by a receiver placed outside the subject (For example, see JP-A No. 2001-91860 (KOKAI)).
However, in the capsule endoscope, it is necessary that the components be correctly positioned among each other in order to obtain a good image within the subject. Particularly, in an optical system that focuses the reflected light incident through the front cover 1b on the imaging device 6, it is necessary to correctly perform the positioning, because the optical system has a direct influence on image quality in the subject.
Therefore, in assembling the capsule endoscope, it is necessary that the correct positioning be simultaneously performed, which makes assembling work remarkably complicated and thus taking a considerable time to assemble the capsule endoscope.